Catalyst of high mordenite content for isomerizing normal paraffins and process for producing the catalyst

Abstract

A catalyst for isomerizing a hydrocarbon cut of high n-paraffin content is disclosed. The catalyst is obtained by controlled oxychlorination of a solid containing at least one group VIII metal supported on an acid mordenite, said mordenite having a sodium content lower than 0.2% by weight, adsorbing molecules of a kinetic diameter larger than about 6.6 Angstroms, having a mesh volume, V, of the elementary mesh from 2.73 to 2.78 nm 3 and a benzene adsorption capacity higher than 5% by weight, said oxychlorination being conducted at a temperature of about 200°-500° C. by means of a gas mixture containing oxygen, water, chlorine or at least one chlorinated compound used in a total amount from 0.5 to 10% by weight of chlorine, in proportion to the mordenite weight. The catalyst may further contain a matrix, the mordenite amount being at least 40% by weight of the total amount of mordenite and matrix.

We claim: 
     
       1. A mordenite and group VIII metal containing catalyst, obtained by a process consisting essentially of gas phase oxychlorination of a solid containing at least one group VIII metal of the periodic classification of elements, supported by a mordenite in acid form, said mordenite having a content of alkali metal and alkaline-earth metal cations, expressed in sodium weight equivalent, lower than 0.2% by weight with respect to the dry mordenite weight, adsorbing molecules of kinetic diameter higher than about 6.6 Angstroms, having a mesh volume V of the elementary mesh from 2.73 to 2.78 nm 3  and a benzene adsorption capacity higher than 5% by weight, in proportion to the dry mordenite weight, said oxychlorination being conducted at a temperature from about 200 to 500° C. by feeding of a gas mixture containing oxygen, 0.03-4% by weight of water, and chlorine and/or at least one chlorinated compound, the chlorine or chlorinated compound being fed amounting to a total of 0.5-10% by weight, calculated as chlorine weight in proportion to the mordenite weight. 
     
     
       2. A catalyst according to claim 1, wherein the acid mordenite is a mordenite whose Si/Al ratio ranges from about 5 to about 50. 
     
     
       3. A catalyst according to claim 1, wherein the gas mixture used for the oxychlorination contains wet air with chlorine and/or at least one chlorinated compound added thereto. 
     
     
       4. A catalyst according to claim 1, wherein the oxychlorination is performed by contacting the solid with a gas containing oxygen and water, heating up to a temperature of about 300°-480° C., then introducing the chlorine and/or chlorinated compound gas mixture in an amount corresponding to a total of 1-5% by weight, calculated as chlorine weight, in proportion to the mordenite weight. 
     
     
       5. A catalyst according to claim 1, wherein the oxychlorination is performed with chlorine and/or a chlorinated compound selected from the group consisting of hydrochloric acid, carbon tetrachloride, dichloropropane, dichloroethane and chloroform. 
     
     
       6. A catalyst according to claim 1, wherein the group VIII metal is selected from platinum, palladium and nickel. 
     
     
       7. A catalyst according to claim 1, wherein the solid further contains a matrix, in such an amount that the mordenite proportion in the total mordenite and matrix amount is at least 40% by weight. 
     
     
       8. A catalyst according to claim 7, wherein the matrix is alumina. 
     
     
       9. A catalyst according to claim 1, wherein the solid contains 0.05-1% by weight of platinum or palladium or 0.1-10% by weight of nickel. 
     
     
       10. A catalyst according to claim 1, wherein the resultant catalyst has a chlorine content equivalent to about 30-50% of the chlorine feed. 
     
     
       11. A catalyst according to claim 1, wherein the resultant catalyst has a chlorine content following oxychlorination equivalent to about 30% of the chlorine feed. 
     
     
       12. A catalyst according to claim 1, wherein the content of alkali metal and alkaline earth metal cations is lower than 0.1% by weight. 
     
     
       13. A process for the production of a mordenite and group VIII metal catalyst, comprising oxychlorinating a solid containing at least one group VIII metal supported by an acid mordenite, said mordenite being in acid form and having a content of alkali metal and alkaline-earth metal cations, expressed in sodium weight equivalent, lower than 0.2% by weight with respect to the dry mordenite weight, wherein said oxychlorination is conducted at about 200°-500° C., with a gas mixture containing oxygen, 0.03-4% by weight of water, and chlorine and/or at least one chlorinated compound, the chlorine or chlorinated compound feed amounting to a total of 0.5-10% by weight, calculated as chlorine weight in proportion to the mordenite weight.